SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3eb0f437dc6be715d0b2f53dec8692232962b8488343e045b5d3a1ea2da6937' 
  AND token = 'djP+a9TRVn4Avrk/TsFaJKgEOoPBnvoEftz67Wf16pw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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