SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6431fa02774f17a35259189558f2641259f054685daf82746446fa93f02fc9' 
  AND token = 'ebEtPcVRg6epvivx+88Ab+SlIOrXw//R5i0acpy9NTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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