SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '127528f0ffad18d227c247d1893357207f3494bc6665567ec1076e1229d02f34' 
  AND token = '//2eUygRFGpRbvKXI/xN1Bj2IliHhYyREpUJ5vPjAXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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