SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f91a763e4e33d19e28e99c254258855e254bcd81d9c1e0e48a7270a2650f314' 
  AND token = 'CyCNpWikcYRdPfY8nSGqQSx6IOTZCrAYbZmSrLdlzf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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