SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6c011015b703d7cd9cbe7599a5b09d147119e1e337f460684d72e3e35659684' 
  AND token = 'd3B0ErCCMCtYr9MrnuwAOwDH3s8S8fvg1e3vvhSIyb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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