SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5bec44fc12cbefd1750ea57d5596345d88aace3737813a8efa8d087dfe99e61' 
  AND token = 'CE2lNj2G7MlaJkfQ+XLgYHQyPpPgSbFNZFlPzBNPC7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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