SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8af41e2f709723e3facb09d09899df8691b9c5f90b7564d0a43af4bec528e08b' 
  AND token = '9MlkqAp+zqaUxtW0G1sQPAhgDO1JAZsWHKTSvVwLn5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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