SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b82826716e3d5cba6724e7f703a63ad9deda9470bbdc78092b341a608f6eb5e' 
  AND token = 'dGnHzFMezKejnO+nY0/PppGmpu/YS7kOB/aTBtbvpjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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