SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4340481f011b2db788b13525b8ff6bccdee136e95472b3c08df0177918d9c82c' 
  AND token = 'ckj6LrHBkVB1wcjwZxmxKGJixmG20H5p+Nav8NyQPpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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