SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb4a908cc765609ee610b051bef75dd895fd867e29fee860de3535e46fa9e4fa' 
  AND token = 'xy5YwijvWaWEXU0/CnfixDlZrvAJIAPvV1GfB5FCBFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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