SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67b01698fe1f53244ce3e6e7f40409fbc28c15e941146383528dc9db42fde7c1' 
  AND token = 'UcA71T0h+iQPFIHRHknyJWzrf7jNZZEtaLa74Ltni9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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