SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40efa84f11af182767c995ee6a697199bd098be5429dab6c864556c0ded1ab9b' 
  AND token = 'QuMaw3XViytMfXlnjvXUjKnwrgtXeNqoMay+sgd5Dkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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