SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a16d2a66c24066d3ef20e58090e376a9d46132082cd454084bf0537cb50ca996' 
  AND token = 'kbW1EAGKgOkBssPZrblpVngMzqBTXc/HlxqbUGuiSdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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