SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f8239a3dfdf73bb41d099fc503f3463bd144a736525383e7d84d2fea872a057' 
  AND token = 't1BfSC4jqwBV8HaDM2AFfAEZPt6H+t30zVaQOL9v9bU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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