SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b631f7b45783d646ab17b0fb1ae92a3902fe44f1e2cee67a25920a20014dea97' 
  AND token = 'GMxbhLFlDmaV0f15Yl10WNVgRKEDQWtLW4r4DTnvPmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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