SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b508a6ae59b148f33ef41be9437da60cec1df214a0afce8da3a08ff5fd093c18' 
  AND token = 'z/bL+nBTbVpYlSQSydLv2QvxtmsqI2UPyLzTu0sa0eU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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