SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a84768a8090a0594689d79aa0735a2850119e9d4f7f7bf4323c29fe10995cdf2' 
  AND token = '3+wxKct3cokkwzBr3ytK7JIQLaaqrBqyZw64sP2sPeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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