SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398ecc6ef0c0d22729c415ab5db75ccfa5119c7ba5fd6befc0b7d70143daa86d' 
  AND token = 'RtBDS1KdAcf+zekjXCmuWuFHwNHbVpl5QYzchyS/OpA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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