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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd23e87ec1b2ae68100944cafda1a2228534a3a75b7aff81247bb42aadb431338' 
  AND token = 'h0AyRDeBpNSSzvFQQ3eIrn89Gzn6qUbFIW+Jp8rtwyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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