SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '900a56b686cd62f0d6918f89ccf1fd2687889392c3f7935bce19a4d99d9a34f8' 
  AND token = 'DthH/x1cDn6YQ63zVKa/rjOjqQzruq4HEUqbWZMjeTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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