SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b3934a3144a56d68d9846ea26888d7f1238edcfd84b489163c33e06cddd867d' 
  AND token = 'jUe/ANONd5tl3UWitesYtBPHKvogv2fH3+y4CPT0lCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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