SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb475977133c3ef5c3c464e75d372cfe380b85950335cfa1463bbd2afeb44c6c' 
  AND token = 'vpPWsZUo1QVeJYXTPMU3rrxcE613mBTR5CgudEVqB9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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