SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '247c60912958d8b5426317d5c21db20f580166648b92f983c36c558a84cfbbad' 
  AND token = '8cgjw+ZCgf2rVzPzC/d7kTiQirnnBixILy4wphlcVAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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