SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f384502f1ce89c873e00ae25819c83794e478fc4d7f15e0295da05a58cddd463' 
  AND token = 'UUFjzERXNQnGRW2X3yQHAyQZboLByQjz0F7mukK08HU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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