SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1646313cc8fe4aa65de54e5d6587c105d14183604e90233d219c75535e4181df' 
  AND token = 'JU7vvm0IZbMGqvSrZtWYB1tiPpCSl3D1wMj33uApcQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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