SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af6719a303b213b01e6824add9a32a1cd2b0b42951dc9eae60eabad8972d091c' 
  AND token = 'X2flDJY0Xk710qcMvg19mx9TzBW4OhlVtdMHnaynO2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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