SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8ae47242bd76fa259080f39eb81cfcfe2565c165373174b5421e25d46c920f0' 
  AND token = 'qWnd2E4Bw/SA0gu1uQuVXWDSnZOmDcxLbIMxKzT9NJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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