SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd0377a8f721a36c117def8d26231b0191933857a610384ad9d98a102e52b7d4' 
  AND token = 'iF5o/YFMVKPtGlwqYnJZ3jFBTePMMmsxd+IauGqFm2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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