SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '850f7820bbdde9e401a567383743230297b4bd0529e139462a0b6ea0b6023237' 
  AND token = 'iutqmwGo7LuQvOTh1PLq+1Z/htNf1XveV2dwzpVvXGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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