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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '305cbffbf71ad166f43fe4aa91ce96b71541472df3cdedcf59b8f71196f515ad' 
  AND token = '6fLG4cIpQRzGdHedOcUsag0bXlR+34CcEzHpw/Z9ScQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}