SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddd4ce03a702f3d37f99da5991ecfdac8341ab9ba73263af858d18aa312464a1' 
  AND token = 'eVdZtPn/MuqYlqu3EFZ1GG42yaL3pCt4kmj2nGVXIrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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