SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40df1615bd4a288a768c09b4b31234ba97ccea254c515ecc8a66bfb9c4d69239' 
  AND token = 'jFtVDxq7JpswzPcrtiIVqtDdv1HsMCBw8kCLijbb4RM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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