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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f6fb0c80e5651adda7dc3c367a5a48ee3686c9399ee6d8ec6bc68a52207a2b5' 
  AND token = '6XMtaIkzJQh0ZdC0aDYoSFZdqnCI9JGrJRI7owb38x8=' 
  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"
    }
  }
}