SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bec918fc4d5a1be18a2681529558370e40bccb427ddb6323ef00c79a0bb3787' 
  AND token = '3v7O1bJC4GuMM4mmzP6QJ7A79W1rfE4Jk4ZBp4m61OQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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