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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a52d4afe3cd0fbcce87dfa12b9f2fa26928e525b36d76ae4387e255e4b9031df' 
  AND token = '6s7Tq8FpsYP6oAWZsbaHxq7Ak5oRYF52hPx0BDQ2KsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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