SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4c68ec3132a8c5a3d6af1d1a90bbf75b675436c7432d8a37b1bc82bb61bc4a4' 
  AND token = 'VOqQP/uQiTv3P7/cWikG9VRvgQbkU4kOagv3dBy4L2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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