SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b514cc63bf743a3e21c32381eb4309fecd081ab26c0f96c256f6c5026c2a3b38' 
  AND token = 'xuOiz7CpoHqyKAVl6AtkpB4GcQxXjvvWay30zHAVMtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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