SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c391e98d01c613cbccdd66f925927a05c50b75fe6f984c3df28ad76e24df37bf' 
  AND token = '6vA5mriVYjItJF9wOR+Seg0kxQdRreEO8ovAGrcDIeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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