SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9faeba6c96f193d6cdbde28363aac69f26fe0012422e21167efdfaf4fad2db7' 
  AND token = 'a4r1CudxCJy5sgLmTolyCq+EEOU8ZygsXGecNa26F7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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