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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff1900d546e29faf49013d2e62a6a73485847ed82ed0e835d83f266b67b810cb' 
  AND token = 'C4kSQE+QtQkDg1OzBNBWc5kJyUEiUb4bKPwtR00b3Iw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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