SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d75364675b47c21f04743f4c8f6d5828fb51267928e2dac4fdd9f685f962d68' 
  AND token = 'JrH10X3sJV4XPkq+7vmeZ+Lz3F7GmlIItiUZhkmghi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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