SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44c9146522628bcbe606125e7d344c6932b6e3e506090110ff412386926d0d6f' 
  AND token = 'ieDQSCbVQZumwT5VxdVO5s/jW3pRqnVfB9aJtSG6WvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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