SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d91c4b764316f06ff0232218e750f435835d767e2443b36ea69347c07f30da1' 
  AND token = '6zCUL+uWm7Dt20YkI1zQxo/N7YCEvbM/g0aCgQHggYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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