SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2d0554825c16337060a7f8884e5281b6dfb08f04aa44c32c3ad66dfa638d364' 
  AND token = '4sGaRRPC9fmiea20UCUhgRb4vw1OU+XkuEGeU0L8x6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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