SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '417126a837e3a7c812ee11ac040e470c55a1145f683c4adf9a913357658dd52c' 
  AND token = 'uFlTAEe8HMDxDLdKMqWccaclvOd/m9p2p/3BPHLObz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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