SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd57acb1bdfd3ea974c8c0f2efd1d3ff598e25d6787d8e3157fac08feca284f9e' 
  AND token = 'mCo/W6TxmQUrd0xwl/qT8Hy0e9wxoGPsCAQ3eS1ekog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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