SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42d498d97e489c276a5c88d573371d7ef344bc6b0b5f9721db94d84799e321f9' 
  AND token = 'tnCNfGi6ufRGJRroZeNqygwI6yp0QkIdqnPkdxCtDYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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