SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8d10a2bdec39e09ff5538f5bc87b8c57cfbb9184d8bc44bde9679913244a4e6' 
  AND token = 'E/kEuBVaGg+yvRcLREsfrwashUYYPqlMXVLdwXcc1Wo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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