SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fbea5112dd08829469b703eea9a7d7d74f3fbcdb4d09050311e72b0288cae13' 
  AND token = '6mPKDu33yBguRryy24uPd8FabEzTzKkwRY3eXENLGoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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