SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef354d8a79ea1a3fea72670d1aa92b20531d990feba36e3313e488679f4ea402' 
  AND token = 'w7Xq7H5d4+lavUSlD6+sDQ0mFVtMrhSKjZ5CNzKu/Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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