SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a223221441b2358103a5dd16a7a4383c2891f7556ea29889f62e9f5ae2c739fa' 
  AND token = 'E/PORS9JM7jflu78Ey+EVGH8tCsHgm9LHgGVGNoph+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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