SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69fb75a9d28f50d72a15b6734ba4a18fffea91d45368f3601f0affbcf123ec20' 
  AND token = '+8oxKMLWoZnDgoTJ+8wPxlFnZjIR//HGMWfl5AMln7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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