SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3578892058a83db1c156b867696dce1b48df393792237925faef551f2bfa3411' 
  AND token = '2rjpbSHtx+psLJjnUcBdllNePTZBs158HDQzYCYFlpA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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