SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f783d9b3622566952933b1edbf6999c5f5a84545da3241b39985a7ccfbd3152' 
  AND token = 'C4TClydJYOB80FCxCnOtZt4WFleTpAuysFjFpAlyf6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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