SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '240c195e56fa6c011bd65aa0eebfcb0adc764f285b63a673d769554405f5e496' 
  AND token = 'YZiZYsyw2SP8CRPGLs7uSBIrT1istSuh8PDYv5BNENM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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