SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6355d140dbc237aafc3150def3fd722491092f73df695726c76bc0ccf2ebd2a' 
  AND token = 'qgYiBJuAkc3TyyzNjyi98xhOJATad/YJZfzkPcrw1W0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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