SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53683c39625ce112b8eb634407244005882d21caff1bbdd17c8b41f0388cb25e' 
  AND token = 'qufSFMjKiyryuB5QtAg1MmIcZ1aoMCfj0nsm6z3Eqas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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