SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dec31356472c6df5bc0ae4b0c529bdf4a1c3a77991952f50fed2a5cad3f8e23d' 
  AND token = 'eu+87qRvI1+mDJ6CMws7x2QBkstqv259SwSLgCCGZ/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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