SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e99dc0f7a70f42710df4860fe461d827d65d731e58340005962727356a4848c1' 
  AND token = 'c9cYGedVuRi6e3hSjj5dFUj2/mtK5nsDCK6Sg+zacwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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