SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff5ace9405b71fdb54154cc7f5b11a7543fe8e3052154b352463308a55dedf02' 
  AND token = 'dZkYRFZ5w6/yH2toH/mGWgVDcxDWiR0adtdSZouU2h0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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