SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '968b87c5807ad9fa67e6abf8d410c6b2cf95396bfcdcc84c047106142c972299' 
  AND token = 'vgBH62lulkMxkPALYYI5VxEUFluDF/35nTBvb/6JYzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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