SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70306be32293666afc61857562a5421d7e1710660f6fbfa840bfc50e2f952745' 
  AND token = 'N+bE9D/utuBxEr6wwuE+ik4VZpXFjs7OadWK0WJqjGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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