SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '520dcbef434ff746c9828ad6e064637dea7e21afb03ab176c0bb9892fe29dcd7' 
  AND token = 'V9dsTzEjO+uuJU98PHBx3WivAy/bsi8sXEC+DZgHqQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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