SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73c8f4146fb4472c3b3918a0c11905a4126607b14b43671d4b4a52c0fd6fd4a5' 
  AND token = 'GUcgfUV5nZFt7eJ5zRCP8hHt+C4XQaGOHQwy+2rGKwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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