SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d2e0f1dc78c1d0821fa1971bf1c174e2d40077d11ccad0d20deb62baa3da8ff' 
  AND token = 'rkMXwRMXTCxU9W+z9Cyzj9TS0YBjdrX+xO2SjroTzQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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