SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd649ac6902abe8ccdd8300efc91fec58fda42e5a3c88f0def2b619ce494fd0dc' 
  AND token = 'jO3xOFYKLL3h/JB3KZJyIIqqPjbP+sxFBE9hTEZxCeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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