SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fc316e89317cbb3cc6519a004dcee79f5d8714f01c905e6ce978e158a373e6c' 
  AND token = 'vFnXklZjhntVrys0B2VMEbURwMapTTCBNvnnGj/ieKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}