SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f2d8d25cd4f586b6d160d893949467626fd76ea3593b3994f10d60a9097c5a4' 
  AND token = 'w8JdlQYPRQA8YzXGutSGfYHNXqmKaH1hDbC97/zTKfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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