SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd29049f9e37143b0d28fc30addfa523a873931dba13555484def987696c1ef99' 
  AND token = 'RrCDCsSvahTkUn+LvgBUn/+v6tgvtwZwc40Q5Y5EZkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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