SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b52082586829f93175ebe92b29b309cf1bb4c70014d21d91df45548420939baa' 
  AND token = '3CqqQvV7fYzXM+Urty2PSNYgn2HxpVfG+demuMjJpRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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