SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e348c5d9b6670d5e2a9521ad914365e6e2aab2b2d7831bcb4a8d4226d3d6b378' 
  AND token = 'Zb0u8DJLkFHH68Gxl/flqi3uBEwsjDXzZiX35Mhtmrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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