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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef6fbc77c32c05ddbdb2afe68a62442924f28833fcbada6d49c2974e177142a4' 
  AND token = 'U7GU2gJ6fWBCtaFBsRxPHa+grAisy72TqyoAmVNrrp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}