SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b8ffc7ec868db1e426897d60d227fa5441d5e1180eefe476373b513f879bd28' 
  AND token = 'x/YFN6s6gWFusBHNMtj/ogB2CS+MqWxxvYfzH5psbEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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