SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73de0f2c57c2d0888fb343e6465b4fffbc4e875ef2b890c63c5c31694b6d0567' 
  AND token = 'jxZiWkPFDVJy2qc+NiPjExe6VCEzCTDFG5vnZ8O/Gsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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