SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e91eb481e9978aa9375a4805f11d90a113a422d42f7c32b2659b74c7640dbc2' 
  AND token = 'DEYOwWuFIu4Nl8W+rWaIPt00ZDHmN2Ot7Qk8SDb0nNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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